Earth-like planet -- sorta -- spotted in Alpha Centauri

European astronomers discover the closest-known exoplanet found so far, and it comes with a few surprises. Like, it's a little warmer than our planet.

So close, yet so far away. ESO

Roughly 25 trillion miles (or 4.3 light years) from home, astronomers have found that the Alpha Centauri star system hosts a planet with a mass similar to that of Earth. Galactic geeks may recall references to this star system in "Star Trek," "Avatar," "Transformers," and countless other fictional entertainment.

The planet, officially named Alpha Centauri Bb, orbits Alpha Centauri B and took more than four years of observing to fully classify.

"This result represents a major step towards the detection of a twin Earth in the immediate vicinity of the sun," said Xavier Dumusque, who served as lead author of the planet-discovering study, in a release.

The out-of-this-world findings, published today in the journal Nature, indicate that the newly discovered planet contains a mass just a little bigger than Earth and completes a full orbit about every 3.2 days. Don't expect this planet to serve as an intergalactic pit stop in future travels -- Bb is closer to its host star than Mercury is to our own sun -- as it has an estimated surface temperature of at least 2,192 Fahrenheit.

Researchers first found the planet using the HARPS spectrograph on an 11.8-foot telescope at ESO's La Silla Observatory in Chile by picking up "the tiny wobbles in the motion of the star Alpha Centauri B created by the gravitational pull of the orbiting planet," according to a press release. These wobbles, the most precise ever detected and caused by Bb's gravitational pull, move the star back and forth about 20 inches a second.

"This is the first planet with a mass similar to Earth ever found around a star like the Sun," said Stephane Udry, who served as a co-author of the related paper. "It may well be just one planet in a system of several. Our other HARPS results, and new findings from Kepler, both show clearly that the majority of low-mass planets are found in such systems."

 

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